Remove the dask tutorial notebook for now

[mfisher87]

The dask tutorial notebook is not linked in the Mkdocs nav. Relevant discussion: #568 (comment)

• Why was it removed from the nav? It wasn't! It was added as a comment to remind us to add it to the nav later when it was more complete.
• Do we want to bring it back? Yes, but in a different form.
• What needs to be done to bring it back? _@betolink working on it as part of smart_open (`smart_open()`: dynamically improving fsspec caching strategy. #527) work

Decision: Remove it for now!

[mfisher87]

The tutorial was never added as a nav item, it was always commented out: dab9da4

@betolink can you shed some light on this?

[betolink]

This was an initial toy example with Dask, I'm working on a version that works independently of Coiled but I don't think it will be ready until next month, hopefully by then we'll have smart_open=True released.

[mfisher87]

Should we remove this notebook so it can be replaced with the Coiled-independent version later?

[betolink]

I think so.